Charging lithiums new boat..

[john_morris_uk]

My previous boat had 40w of solar, which kept the batteries topped up on the mooring and would replace my use over a winter weekend working on the boat ready for the following weekend, but my needs were modest. I wouldn't run a fridge on less than about 150w of solar.

In general, unless a boat is only used at weekends and spends the rest of its life hooked up to the mains, I'd fit as much solar as practicable - there's a certain contentment watching the sun go down in a quiet anchorage and knowing your batteries are fully charged, and a certain anxiety watching the batteries discharging a bit more each day because you haven't got enough acreage of solar.

Agree 100%. More is better without getting to the oneupmanship of how much have you got. We have a little over 400 W but our usage is very different as we live on board for months at a time. The OP has to assess his ppower needs and charging options.

 

[geem]

Agree 50 watts solar is tiny but for topping up the batteries while the boat is on its mooring it’ll certainly help.

Once you make the jump to lithium, the battery charging game changes significantly. If you swap 200Ah of lead for 200Ah of lithium, not only will it be lighter and take up less space, but you almost double the usable capacity. You also no longer need to trickle charge to keep the battery voltage up (to stop sulphation) like you do with lead. With lithium, you have the opportunity to discharge batteries far more deeply with no ill affects.
If you are going to make use of this extra capacity, you need to be able to put the amps back in.
Let's say you discharge 100Ah out of your lithium over a weekend. You would want the battery charged up by next weekend. That means you have to put 100Ah back in in 5 days. 20Ah per day. Assume you can get half the capacity of the solar panel output for 5 hours per day in a good sunny summer day. You should be able to make 10Ah per day. Half of what you need. If you get a cloudy few days the output could be a whole lot less.
Max out the solar and it all starts to make a lot more sense.

 

[pandos]

Connect up a new DC/DC and some sensible amount of solar. 50w is really, really tiny

The DC DC is faulty... That is the issue....am waiting on the supplier to replace...

50w will refill my bats whilst boat is sitting on its mooring unused , and is all I can fit it being in the way and without building an arch or something at the stern.

 

[geem]

The DC DC is faulty... That is the issue....am waiting on the supplier to replace...

50w will refill my bats whilst boat is sitting on its mooring unused , and is all I can fit it being in the way and without building an arch or something at the stern.

What about guardrail mounting? You get built in spray dodgers

 

[pandos]

Agree 50 watts solar is tiny but for topping up the batteries while the boat is on its mooring it’ll certainly help.

Victron kit is usually pretty reliable so it’s disappointing that the 30 amp DC to DC Orion has failed.

I agree with the comments re the Argofet. It’s not needed and the banks can be left entirely separate save the connection will be through the DC to DC which isolates them when it detects the alternator isn’t running.

If it’s the lead acid battery that’s down to 8 V it will already have lost some of its capacity. They simply don’t like being discharged to that level and left. In fact lead acid don’t like being discharged to that level at all.

I assume it’s the lead acid battery down to 8 V as most lithium have a built-in BMS which would turn the battery off when charge level gets dangerously low.

It's the lithium bank is at 8v. The LA starter is perfect....there is a BMS in each of the lithiums,

It's all a bit odd..but would be explained if one of the fuses at the bats is blown..( I am not sure I ever actually checked these individually)

My usage over the weekend was probably typical for me. And if I had 200amps at my disposal or a DC DC it would have been perfect,


Looking back I started off at about 60% according to the monitor which may have only been 20amps..this increased to 60amps after motoring with everything turned on. Then after anchoring for 36hrs with the fridge tv etc. I was back to 20 amps, it ended with zero when I used these amps over about 4hrs of autopilot radio AIS cd player etc...

It's becoming more clear that I have at least three failures I have only 100amps of battery and a faulty DC DC and no solar.

The 50w solar will easily produce over a week enough for me to use on an average weekend, I always have a not of motoring also.

 

[Sea Change]

It's the lithium bank is at 8v.

That should be impossible.
Can you access the settings on the BMS? Even the cheapest and nastiest drop in lithium batteries will disconnect at 10v. I've set mine to 12v because I'd rather preserve the cells than squeeze a couple more percent capacity out of them

 

[geem]

That should be impossible.
Can you access the settings on the BMS? Even the cheapest and nastiest drop in lithium batteries will disconnect at 10v. I've set mine to 12v because I'd rather preserve the cells than squeeze a couple more percent capacity out of them

Sounds like there is more to this than meets the eye

 

[pandos]

That should be impossible.
Can you access the settings on the BMS? Even the cheapest and nastiest drop in lithium batteries will disconnect at 10v. I've set mine to 12v because I'd rather preserve the cells than squeeze a couple more percent capacity out of them

Can't access the BMS, or at least I can't see an obvious way and it is not showing as a Bluetooth device.

Batteries are "Melog", bought from Amazon two years ago by the previous owner.

The bank went to this level, 8.3v, in the past when I left the fridge on for most of a week, At that time I still had access to shore power, in fact that was the first time that I had an indication that all was not well as I thought that there was enough capacity to keep things in operation longer and the batteries came up to fully charged quicker than I had expected. Pity I did not investigate things back then.

Anyway, Amazon has delivered a solar panel and an MPPT along with leads so hopefully tomorrow afternoon will see some "demystification" take place.

 

[geem]

Can't access the BMS, or at least I can't see an obvious way and it is not showing as a Bluetooth device.

Batteries are "Melog", bought from Amazon two years ago by the previous owner.

The bank went to this level, 8.3v, in the past when I left the fridge on for most of a week, At that time I still had access to shore power, in fact that was the first time that I had an indication that all was not well as I thought that there was enough capacity to keep things in operation longer and the batteries came up to fully charged quicker than I had expected. Pity I did not investigate things back then.

Anyway, Amazon has delivered a solar panel and an MPPT along with leads so hopefully tomorrow afternoon will see some "demystification" take place.

8.3v puts you cells at 2v. Below 2.5v you do irreversible damage. The bms is supposed to protect the battery from such events. Two issues.
1. Your cells will very likely be damaged. 2. Your BMS is not working properly. Put both of there issues together and you really need to change the battery for something better. Unless there is another explanation for why you are seeing 8.3v. Are you actually measuring this at the battery terminals?

 

[pandos]

8.3v puts you cells at 2v. Below 2.5v you do irreversible damage. The bms is supposed to protect the battery from such events. Two issues.
1. Your cells will very likely be damaged. 2. Your BMS is not working properly. Put both of there issues together and you really need to change the battery for something better. Unless there is another explanation for why you are seeing 8.3v. Are you actually measuring this at the battery terminals?

It's according to the victron battery monitor and the voltage readout on a USB charger...I'll not be too surprised if they are chucked.

Another possibility is that the battery shut down and the 8.3v is just some residue/leakage from the engine battery and alternator systems...

I went from having an autopilot and an android touch screen which were both functioning properly to no autopilot and a flashing screen on the android. This may have been the BMS as I went near 10v. I can't see these devices functioning below 10v?

 

[geem]

It's according to the victron battery monitor and the voltage readout on a USB charger...I'll not be too surprised if they are chucked.

Another possibility is that the battery shut down and the 8.3v is just some residue/leakage from the engine battery and alternator systems...

I went from having an autopilot and an android touch screen which were both functioning properly to no autopilot and a flashing screen on the android. This may have been the BMS as I went near 10v. I can't see these devices functioning below 10v?

I do suspect there is something else happening here. You might be lucky and the batteries are fine

 

[pandos]

Bit of an update.

Finally got to the boat this afternoon.both lifpo4s showing 7.6v. this was according to my multimeter and the battery monitor. Disconnected and left standing they both individually showed the same.

I rigged up the 50watt panel, mppt and fed it directly to one of the lithiums. Over a few hours of overcast sky, the panel managed around an amp @20v so it put a few amps into the battery. By the time I left the battery was up to 11.8v .

The voltage according to the mppt was identical to the reading from my multimeter.

The lithium will be on charge like this until Wednesday morning It will be interesting to see what a bit of solar will do.

There does seem to be an issue with my battery monitor as after taking out the lithiums I put in my spare battery which was showing 12.7v it's an old 80 amp ordinary lead acid battery that I use for a lead light, portable bilge pump, dinghy pump etc and which has not been charged since April, yet the battery monitor showed 100%charged, even before I changed the setting to reflect the change in battery type and capacity..

Took the Orion out and it really smells burnt just waiting on return instructions from the supplier.

 

[Sea Change]

I can't see how your BMS allowed the batteries to get so low. Do they actually have a BMS?? We're they left standing for many months without charging? The small parasitic draw of the BMS itself, plus cell self discharge, could in theory drop the battery voltage lower than the normal cut off point. But it would take months.

 

[pandos]

I can't see how your BMS allowed the batteries to get so low. Do they actually have a BMS?? We're they left standing for many months without charging? The small parasitic draw of the BMS itself, plus cell self discharge, could in theory drop the battery voltage lower than the normal cut off point. But it would take months.

According to the literature they have internal bms.

I have no reason to disbelieve this, although there is no physical or Bluetooth access to the bms

No they were not allowed to go flat for months. They were in use keeping my boat on a straight line and running the usual electronics, until they nose-dived to this level.

Obviously I have questions about the how the victron battery monitor assesses the remaining capacity, given it's behaviour with a semi flat flooded lead acid battery...but this will need some investigation.

 

[geem]

According to the literature they have internal bms.

I have no reason to disbelieve this, although there is no physical or Bluetooth access to the bms

No they were not allowed to go flat for months. They were in use keeping my boat on a straight line and running the usual electronics, until they nose-dived to this level.

Obviously I have questions about the how the victron battery monitor assesses the remaining capacity, given it's behaviour with a semi flat flooded lead acid battery...but this will need some investigation.

How often were you charging them? Self discharge rate of lifepo4 is 2-3% per month.

 

[PaulRainbow]

There does seem to be an issue with my battery monitor as after taking out the lithiums I put in my spare battery which was showing 12.7v it's an old 80 amp ordinary lead acid battery that I use for a lead light, portable bilge pump, dinghy pump etc and which has not been charged since April, yet the battery monitor showed 100%charged, even before I changed the setting to reflect the change in battery type and capacity..

Took the Orion out and it really smells burnt just waiting on return instructions from the supplier.

Nothing unusual here. The battery monitor cannot possibly tell the SOC of a battery that you just connected to it. You have to set it for the correct battery capacity and fully charge it to sync the SOC. It will also need to be periodically fully charged to re-sync the SOC as over time it will drift.

 

[pandos]

Nothing unusual here. The battery monitor cannot possibly tell the SOC of a battery that you just connected to it. You have to set it for the correct battery capacity and fully charge it to sync the SOC. It will also need to be periodically fully charged to re-sync the SOC as over time it will drift.

I understand that, I did the setting up and syncing with the lithiums, but it was still showing 50 % when they were clearly at zero.

Having been set to have 200amps of lithium I was surprised to see it think it had 100%

When it really only had a partially charged 80amp FLA..

How often were you charging them? Self discharge rate of lifepo4 is 2-3% per month.

They were fully charged and synced when I left the yard in mid June. Because the Orion was not usable they were not charged consistently since then, but they had little enough use.

They were charged for about 6 hours on the weekend they died. (I bypassed the Orion and they were taking about 20 amps at modest revs)

But when they were nearly flat they were taking 50 amps at high revs, so at that stage all charging was abandoned until last night's solar.

First image after a few hours of dull sunlight. Second image just before I took the cover off the solar panel..

 

[PaulRainbow]

I understand that, I did the setting up and syncing with the lithiums, but it was still showing 50 % when they were clearly at zero.

Having been set to have 200amps of lithium I was surprised to see it think it had 100%

When it really only had a partially charged 80amp FLA..


They were fully charged and synced when I left the yard in mid June. Because the Orion was not usable they were not charged consistently since then, but they had little enough use.

They were charged for about 6 hours on the weekend they died. (I bypassed the Orion and they were taking about 20 amps at modest revs)

But when they were nearly flat they were taking 50 amps at high revs, so at that stage all charging was abandoned until last night's solar.

First image after a few hours of dull sunlight. Second image just before I took the cover off the solar panel..

The battery monitor just "counts" amps in and out of the battery. There will be losses that it can't entirely take into account, and it cannot measure natural self discharge, so it's slowly getting more and more out of step with reality. But every time the batteries reach 100% SOC the monitor re-syncs to 100%. The more time between full charges the more inaccurate the SOC reading will be.

If the batteries are faulty, which in your case they look very suspect, the monitor cannot account for that. If you change the battery, how do you expect the monitor to instantly know the SOC ? It cannot. You need to set the battery capacity and fully charge the battery, then manually set the SOC to 100%, after which, all of the above apply.

 

[pandos]

The battery monitor just "counts" amps in and out of the battery. There will be losses that it can't entirely take into account, and it cannot measure natural self discharge, so it's slowly getting more and more out of step with reality. But every time the batteries reach 100% SOC the monitor re-syncs to 100%. The more time between full charges the more inaccurate the SOC reading will be.

If the batteries are faulty, which in your case they look very suspect, the monitor cannot account for that. If you change the battery, how do you expect the monitor to instantly know the SOC ? It cannot. You need to set the battery capacity and fully charge the battery, then manually set the SOC to 100%, after which, all of the above apply.

I understand that they count in and out..it was synched manually at 100% after the batteries had been charged on a victron 30amp mains charger. (Both the charger and the monitor showed 30 amps flowing )

I think the monitor is showing incorrectly due to its tendency to automatically sync, whilst getting low level charging for short periods when the Orion was connected..

The following is from victron:

"Example:

In the case of a 12V battery, the battery monitor will reset the battery’s state of charge to 100% when all these parameters have been met:

The voltage exceeds 13.2V,

the charge current is less than 4.0% of the total battery capacity (e.g. 8A for a 200Ah battery) and,

3 minutes have passed while both the voltage and current conditions are met."

I can well imagine these conditions being present once the batteries hit 70% with the engine ticking over for a few minutes.

I have the Orion unit at home waiting on return instructions. It smells very strongly of burn, and looks a little distorted, if it wasn't so expensive I'd open it up for a look..

One battery has been on the solar for about 40 hours. Two nights and one dull day. History below...drop overnight was 0.08v..

 

[pandos]

I do suspect there is something else happening here. You might be lucky and the batteries are fine

One battery has been charging away merrily on the small solar panel. I'll see how it has fared on Saturday which will be hopefully more than 50 amps charged.

The other I took home and put on an old style mains charger for a few hours. It gradually increased in voltage and topped out at about 13.7 ( whilst still on the charger before I became impatient...)

With the charger off, after about 5 mins the battery was at 13.2v I put a 55w car head light on it, 61/2 hours later it is still as bright as it was at the start. The voltage reading at 13.08

Some sources suggest that 13.2 indicates 70%.charged, at 13.08 about 35% charged. So a drop of about 35%.

6 1/2 hours @4 and a bit amps suggests I have taken out about 27 amps so things may not be too bad.

Is there a best method for charging and testing Lifepo4 s..